The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
An internal combustion engine combusts mixed gas in which fuel and air are mixed at a predetermined ratio through a set ignition mode to generate power by using explosion pressure.
Generally, a camshaft is driven by a timing belt connected with a crankshaft that converts linear motion of a cylinder due to the explosion pressure into rotating motion to actuate an intake valve and an exhaust valve. Generally, while the intake valve is opened, air is suctioned into a combustion chamber, and while an exhaust valve is opened, gas that has been combusted in the combustion chamber is exhausted.
To improve the operations of the intake valve and the exhaust valve and thereby improve engine performance, a valve lift and a valve opening/closing time (timing) should be controlled according to a rotational speed or load of an engine. Therefore, a continuous variable valve duration (CVVD) device controlling the open duration of an intake valve and an exhaust valve of the engine, and a continuous variable valve timing (CVVT) device controlling the opening and closing timing of the intake valve and the exhaust valve of the engine, have been developed.
The CVVD device may control open duration of the valve. In addition, the CVVT device may advance or delay the opening or closing timing of the valve while the open duration of the valve is fixed. That is, if the opening timing of the valve is determined, the closing timing is automatically determined according to the open duration of the valve.
However, to combine the CVVD device and the CVVT device, both the open duration and timing of the valve should be simultaneously controlled.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.